Motion conversion system

ABSTRACT

A motion conversion system is described. The motion conversion system comprises a first torsional member operative for rotating in a first direction. A second torsional member is offset a distance from the first torsional member, wherein the second torsional member is operative for rotating in a direction opposite from the first direction. And, a lateral member has a lower surface connected to the first and second torsional members. Wherein, translational movement of the lateral member results from rotational movement of the first and second torsional members.

This application is a division of application Ser. No. 11/963,072, filedDec. 21, 2007, which claims the benefit of Provisional Application No.60/871,588, filed Dec. 22, 2006, the entireties of both of which arehereby incorporated by reference.

DESCRIPTION OF RELATED ART

With the evolution of electronic devices, there is a continual demandfor enhanced speed, capacity and efficiency in various areas includingelectronics, communications, and machinery. Many modern devices includemoving components. Efficient operation of these devices may depend uponeffectively measuring movement of their components. Techniques formeasuring movement may differ depending upon the type of system used.Some systems may have rotational movement that needs to be measured. Amicroelectromechanical system (MEMS) is usually a system that haselectrically controllable micromachines (e.g., a motor, gear, opticalmodulating element) formed monolithically on a semiconductor substrateusing integrated circuit techniques. Measuring movement within a MEMSsystem may differ substantially from a non-MEMS system. In addition,there are few motion conversion systems that are applicable to variouskinds of electrical, mechanical, or electromechanical devices. Moreover,any motion conversion system that is applicable to various environmentsmust also be reliable, robust, and cost effective. Consequently, thereremain unmet needs relating to motion conversion systems.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood with reference to the followingfigures. The components within the figures are not necessarily to scale,emphasis instead being placed upon clearly illustrating the principlesof the invention. Moreover, in the figures, like reference numeralsdesignate corresponding parts or blocks throughout the different views.

FIG. 1 is an environmental drawing illustrating a variety of devicesthat may incorporate a motion conversion system.

FIGS. 2A-2D are block diagrams illustrating various implementations of amotion conversion system.

FIGS. 3A-3C are perspective views of the cooperative movement of a pairof the motion conversion devices.

FIG. 4 is a detailed view of the pair of motion conversion devices.

FIG. 5 is a cross-sectional view of a two-layer implementation of a pairof motion conversion devices.

FIG. 6 is a cross-sectional view of a one-layer implementation of a pairof motion conversion devices.

FIG. 7 is a flow chart for a motion conversion technique.

While the motion conversion system is susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and subsequently are describedin detail. It should be understood, however, that the description hereinof specific embodiments is not intended to limit the motion conversionsystem to the particular forms disclosed. In contrast, the intention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the motion conversion as defined by thisdocument.

DETAILED DESCRIPTION OF EMBODIMENTS

As used in the specification and the appended claim(s), the singularforms “a,” “an” and “the” include plural referents unless the contextclearly dictates otherwise. Similarly, “optional” or “optionally” meansthat the subsequently described event or circumstance may or may notoccur, and that the description includes instances where the event orcircumstance occurs and instances where it does not.

Torsion generally refers to motion resulting from twisting one end of anobject in one direction about a longitudinal axis, while the other endis held motionless or twisted in the opposite direction. Torsionalstiffness is an inertial force that may hinder an object from torsionalmovement. When this stiffness is overcome, torsion may be used tomeasure movement (e.g., road movement) even when the movement isirregular, or non-uniform.

The present motion conversion system may measure movement by convertingrotational motion to translational motion. In general, this systemprovides a reliable, efficient conversion of rotational motion intotranslational motion enabling a wide range of applications, such assensor applications. To accomplish this, the motion conversion systemutilizes a hinge architecture that is space-efficient and compact with ahigh degree of design control and optimization. Furthermore, this motionconversion system may be easily implemented in a wide variety ofcost-effective commercial semiconductor fabrication processes. In oneimplementation, the motion conversion system includes two motionconversion devices, or torsion hinge elements, offset by a finite, fixeddistance. The torsional rigidity across a motion conversion device, ortorsion hinge element, is independent of deposition stresses andvariances. Thus it is uniform. Since the motion conversion system, ordual torsion hinge, is in an offset relationship, this renders theseparation distance of the offset torsion hinges an optimizable (ortunable) design parameter. The rigidity of each torsion hinge elementwithin a design may be individually adjusted to provide a desiredeffect. As a result, the physical relationship of these hinge elementsconvert rotational movement of an assembly into a linear translationalmotion, without reliance on complicated, multi-component assemblies.

This motion conversion system may be integrated into a host of devices.Turning now to FIG. 1, this is an illustrative environmental drawing ofa variety of devices that may incorporate a motion conversion system100, such as MEMS device 110. This device may have freely movingelements that may move translationally, rotationally, or a combinationof these. Often, the translational movement of an individual sensingelement within this type of MEMS device 110 is dependent upon theeffective conversion of the rotational motion of these freely movingelements. Since the MEMS device 110 includes the motion conversionsystem 100, this device may more easily extrapolate and process movementdata. Examples of these kinds of MEMS devices may include pressuresensors, accelerometers, inertial sensors, and the like.

More specifically, the fabrication of MEMS device 110 may begin with thefabrication of a complete complementary metal-oxide semiconductor (CMOS)circuit. Since the motion conversion system 100 uses torsional motion,the same fabrication processes may be used for the remaining portions ofthis MEMS device. In other words, these portions, or the MEMSsuperstructure, may use the same CMOS fabrication process, which enablesharmonization between the underlying circuitry and the superstructure.This harmonization reduces effects associated with transitioning fromone material to another. More components can be within a same area. As aresult, the implementation of a single chip module becomes more likely.

Returning to FIG. 1, the motion conversion system 100 may also beintegrated into other devices. These devices may include a microphone120, speaker 130, electromechanical device 140, and the like. In fact,the motion conversion system 100 may be implemented in any kind ofsystem where translational motion is desired, such as variable capacitor150.

The motion conversion system 100 may be implemented in variousconfigurations as more clearly shown in FIGS. 2A-2D. Each of theillustrated motion conversion systems includes one pair of complementarymotion conversion devices, such as motion conversion devices 205, 207.FIG. 2A illustrates a motion conversion system 210 that only includesthe motion conversion devices 205, 207. Additional details regardingthese complementary motion conversion devices are described inadditional detail with regard to FIG. 3. Each of these motion conversiondevices may be a torsional hinge element. The complementary motionconversion devices 205, 207 may be collectively referred to as adual-offset torsion hinge. In addition, either one, or both, of themotion conversion devices that form the dual-offset torsion hinge may bestationary. For the sake of illustration, neither of the motionconversion devices 205, 207 is shown as stationary. In contrast, themotion conversion system 220 of FIG. 2B includes one stationary, orfixed, motion conversion device and one non-stationary motion conversiondevice. FIG. 2C illustrates a motion conversion system 230 that includestwo stationary, or fixed, motion conversion devices and onenon-stationary motion conversion device. This implementation illustratesthat a motion conversion system may include either an even or an oddnumber of motion conversion devices.

FIG. 2D depicts a motion conversion system 240 that has four dual-offsettorsion hinges. While this system includes four of these hinges, thenumber of hinges included in a motion conversion system 240 may be 6, 3,10, or some other suitable number. In fact, the number of hinges may beselected to achieve some overall design objective. In the motionconversion system 240, each dual torsion hinge includes one stationarymotion conversion device 243 and one non-stationary motion conversiondevice 245. As described in greater detail with reference to FIG. 3,rotational movement of the motion conversion devices 243 may cause acorresponding translation movement of the motion conversion devices 245.Since these devices are not stationary, they may freely move verticallyor horizontally. When a lateral member 247 (e.g., a layer, lamina, orthe like) is attached to the motion conversion devices 245, thesedevices may collectively displace the lateral member 247 vertically orhorizontally when they are working in concert. For example, the motionconversion devices 245 may vertically displace the lateral member 247.The amount of this displacement may be customized by altering the numberof dual-offset torsion hinges, the relative positions of the dual-offsettorsion hinges, the types of motion conversion devices (e.g., fixedmotion conversion device) within these hinges, the relative positions ofthese motion conversion devices within each dual offset hinge, and thelike.

Turning now to FIG. 3A, this figure illustrates the cooperative movementbetween motion conversion devices within a motion conversion system,such as an offset torsion hinge 300. As mentioned with regard to FIGS.2A-2D, a motion conversion system (e.g., motion conversion system 230)may include at least two motion conversion devices that operatecooperatively. Similarly, the offset torsion hinge 300 may includemultiple motion conversion devices, such as 3, 6, 11, or some othersuitable number of motion conversion devices. As an example, the offsettorsion hinge 300 includes two motion conversion devices labeled 310,320.

The offset torsion hinge 300 includes a stationary motion conversiondevice and a nonstationary motion conversion device. The stationarymotion conversion device has a stationary hinge support 310; thenonstationary motion conversion device has a movable hinge support 320.A lever 330 is pivotably connected to the stationary support 310 andfixably attached to the movable support 320. A lateral member 340extends from the lever 330, with a tongue portion of the lever 330captured between a bifurcated portion vertically spaced from a crossportion extending between the bifurcations of the bifurcated portion.When this lever pivots about a hinge axis defined by the stationarysupport 310, the lever 330 vertically displaces the movable support 320,which correspondingly displaces the lateral member 340. This movement ismore clearly seen in FIGS. 3B-3C. FIG. 3B illustrates how this lever'spivoting in the direction shown by the arrow causes downwarddisplacement of the movable support 320. This downward displacementproduces a corresponding downward displacement of the lateral member340. Similarly, pivoting the lever 330 in the opposite direction causesan upward displacement of the movable support 320 and the lateral member340 as shown in FIG. 3C.

As illustrated in FIGS. 3A-3C, the offset torsion hinge effectivelyconverts rotational motion to translational motion. More specifically,the pivoting motion of the lever 330 produces a translationaldisplacement of the movable support 320. This correspondingly produces atranslational displacement of the lateral member 340. Thesedisplacements may depend on several factors, which enable thisdisplacement to be customized. For example, the displacement may dependon the distance between the stationary support 310 and the movablesupport 320. Additional information regarding customizing thedisplacement is described with reference to FIG. 4.

FIG. 4 is a detailed view of a motion conversion system 400 whenimplemented in a MEMS device, such as MEMS device 110 (see FIG. 1).Though some aspects of this motion conversion device are described withreference to the MEMS device 110, the motion conversion device 300 maybe integrated into many other types of devices as described withreference to FIG. 1.

In FIG. 4, a motion conversion system 400 is implemented in adual-offset torsion hinge architecture. This motion conversion systemincludes a first segment 401 that has a first MEMS component 402 coupledto a second MEMS component 404 by a hinge element 406. Though not shown,the motion conversion system 400 may include numerous other motionconversion devices, as described with reference to FIGS. 2A-2C. Forpurposes of explanation and illustration, the MEMS component 402 may bea freely moving MEMS structure (e.g., an inertial sensor component) andthe MEMS component 404 may be considered a fixed support structure.

The relation among the first MEMs component 402, the second MEMScomponent 404, and the hinge component 406 is described in greaterdetail. A first end 408 of the hinge element 406 is coupled to thecomponent 404 at a first attachment portion 410 and a second attachmentportion 412. The attachment portions 410, 412 are in opposing relationto one another on opposite sides of the end 408. They are also offset bya distance 414. A second end 416 of the hinge element 406 is coupled tothe component 402 at a first attachment portion 418 and a secondattachment portion 420. Like the attachment portions 410, 412, theattachment portions 418, 420 are also in opposing relation to oneanother on opposite sides of the end 416. They are offset by a distance422.

Within the motion conversion device 400, the range of motion may becustomized for optimal performance. There is a clearance distance 424between the component 402 and the component 404. Together this clearancedistance and the length of the element 406 may be selected produce adesired range of motion. More specifically, the distance 426 between theends 410 and the end 418 may vary the desired range of motion. Thedesired range of motion corresponds to the displacement described withreference to FIGS. 3A-3C. In other words, the clearance distance 424,the length of the component 404, or the distance 426, may be selectedsuch that a desired displacement, or range of motion, is achieved.

FIG. 4 merely illustrates one design of the illustrated components,though numerous alternatives may result from varying this illustration.For example, the form factor and geometry of the hinge element 406 maybe varied greatly for performance reasons. In the embodiment depicted,the hinge element 406 includes a central offset portion 428 that extendssymmetrically and orthogonally from the central section of the hingeelement 406. This current implementation can impact this element'sflexion properties, such as properties that limit a rotational range ofmotion. Altering these properties for the hinge element 406 may affectits movement. To change the flexion properties, many aspects of thehinge element 406 can be altered. For example, the central offsetportion 428 may be smaller, have a different geometry, or the like. Evenstill, the central offset portion 428 can be completely eliminated, suchthat the hinge element 406 only includes a central beam section. In theembodiment depicted, the geometries of the constituent parts of thehinge element 406 (e.g., end 408, end 416, and central offset portion428) utilize right-angled junctions; these parts of the hinge element406 are also symmetric in nature. In alternative embodiments, however,these parts may utilize acute angles, obtuse angles, combinations ofacute and obtuse angles, or various curvatures at element junctions.Alternatively, these parts or portions of these parts may havecompletely asymmetric geometries, partially asymmetric geometries, orthe like. Any of these variations can impact the flexion properties andcorrespondingly impact the movement.

Returning to FIG. 4, the MEMS component 402, the MEMS component 404, andthe hinge element 406 are coplanar structures with identicalthicknesses. In an alternative embodiment, they may not be coplanarstructures. Moreover, the thickness of one or more of them may bedifferent. For example, the hinge element 406 may have a smallerthickness than the MEMS component 402; this MEMS component may have asmaller thickness than the MEMS component 404. In another alternativeembodiment, the MEMS component 402, the MEMS component 404, and thehinge element 406 may be formed from different materials or from thesame material. For example, they may be formed from semi-conductingmaterials. In another alternative embodiment, these MEMS components maybe formed from a semi-conducting material and the hinge element 406 maybe formed from a different material.

The hinge element 406 converts rotational movement to translationalmovement. More specifically, the hinge element 406 is designed andformed such that it converts rotational movement about an axis (B-B) 431(analogous to rotational movement about the axis of stationary support310 in FIGS. 3A-3C) into translational movement in a directionorthogonal to axis 431 and also orthogonal to a shared axis (A-A) 430along which the MEMS components 402, 404, 406 are aligned. For example,a device (not shown) may have the MEMS component 404 fixed for rotationabout an axis (B-B) within it. Movement of this device may elicit arotational movement in the direction of the arrow 432 about the axis 431at the end 408. Since the MEMS component 404 is fixed, the dimensionsand geometry of the hinge element 406 causes a corresponding,complementary rotational movement 434 about an axis (C-C) 433 at the end416. A net effect is translational movement depicted by the arrow 436 ina direction orthogonal to the rotational axes (B-B) 431 and (C-C) 433,and also orthogonal to the shared alignment axis 430. While only brieflydescribed with reference to FIG. 4, a detailed description of this typeof motion was described with reference to FIGS. 3A-3C. The complementaryrotational movement 434 of the first MEMS component will then similarlyelicit a corresponding, complementary rotational movement in the nextMEMS component, and so on, until a rotational movement 438 depicted byarrow 438 about an axis (D-D) 435 is elicited in a last motionconversion device aligned along axis (A-A) 430. (The rotationaldirection 438 indicated in FIG. 4 which is the same as direction 434assumes an even number of MEMS components in the depicted system 400.)

The design of the hinge element 406 facilitates customization of themotion conversion device 400. In effect, stretching, or flexing,portions of the hinge element 406 increases the torsional stress of thatelement. As this element rigidity increases, there is a greaterresistance to additional movement. This resistance is self-limiting. Theself-limiting properties of this hinge element are particularly evidentas the ends 408, 416 are flexed. Therefore, one can select the material,design, and geometry of the hinge element 406, such that a desired goal(e.g., a designated amount of translational movement) is accomplishedusing the self-limiting properties of this hinge element.

While the self-limiting properties of the hinge element 406 is describedwith reference to a motion conversion system 400 within a MEMS device,these concepts are equally applicable to the motion conversion systemsdescribed with reference to FIGS. 1-3C. In fact, the motion conversionsystem 400 is applicable to variations and adaptations depending uponspecific MEMS design or operational objectives. This motion conversionsystem may be easily integrated in most high-volume commercialsemiconductor fabrication processes. To optimize it for a particularsystem, any one of above-mentioned factors can be adjusted including theself-limiting properties.

FIG. 5 is a cross-sectional view of a two-layer implementation of amotion conversion system 500. In this embodiment, the MEMS device 402and the MEMS device 404 are formed in a first device layer, such asmetal layer M4. In contrast, the hinge element 406 with ends 408, 416 isformed in a parallel and adjoining device layer, such as metal layer M5.Metal layer M5 is positioned above the metal layer M4. As mentionedabove, the same material may be selected for both metal layer M4 andmetal layer M5. Alternatively, different materials may be selected forthese layers. The selection of the material for each layer as well asother factors, such as the thickness of the layer, may be done toachieve design goals.

Turning now to FIG. 6, this figure is a cross-sectional view of aone-layer implementation of a motion conversion system 600. In otherwords, this embodiment depicts a hinge element 406 that is coplanar withthe MEMS device 402 and the MEMS device 404. This hinge element is inparallel, but adjoining, planar relation with these MEMS devices.

Turning now to FIG. 7, this figure is a flow chart 700 for a motionconversion technique that can be accomplished with any of the previouslydiscussed motion conversion devices. This technique effectively convertsrotational motion to translational motion. Any process descriptions orblocks in flow charts can be understood as representing modules, orsegments, which may include one or more executable instructions forimplementing specific logical functions or blocks in the process.Alternative implementations are included within the scope of theinvention in which functions may be executed out of order from thatshown or discussed, including substantially concurrently or in reverseorder, depending on the functionality involved, as can be understood bythose reasonably skilled in the art.

The motion conversion technique of flow chart 700 begins at block 710 bypositioning a first support. This first support may be either astationary support, movable support, or the like. In fact, this supportmay be a support within any of the motion conversion devices describedwith reference to FIGS. 1-6. Selecting the position for this support maybe based upon certain system related assessments, such as the areaavailable and amount of movement desired. For example, the position forthis support member may differ when it is within the microphone 120 thanwhen it is within a MEMS device 110.

Block 710 is followed by block 720. In this block a first lever ispivotably coupled to the first support. In other words, this lever iscoupled to the first support in a manner that enables the lever to pivotabout the first support. The physical properties of this lever as wellas the manner in which it is coupled to the first support may beselected to comply with design objectives, system constraints, orperformance objectives. An example of this lever may be lever 330described with reference to FIG. 3 or the hinge element 406 describedwith reference to FIGS. 4-6.

Block 730 follows block 720. In an alternative embodiment (not shown),block 720 and block 730 may be completed contemporaneously. In block730, a second support is positioned at an offset distance from the firstsupport. Like the first support, the second support may be a stationarysupport, movable support, or the like. In addition, the offset distancebetween the first support and the second support may be selected togenerate design constraints. For example, the offset distance betweenthese supports may be selected to produce a certain amount oftranslational motion from rotational motion.

Block 740 follows block 730. In an alternative embodiment, block 730 andblock 740 may be completed contemporaneously. Block 750 follows block740. These blocks work together to help facilitate the conversion ofrotational motion to translational motion. As the lever pivots, itcorrespondingly moves an extender coupled to the lever. Moving theextender displaces a translational member coupled to the extender. Theextender and translational member can be jointly referred to as thelateral member 340 described with reference to FIG. 3. Selecting thephysical properties of the extender and the translational member mayalso be based on design constraints. For example, the dimensions ofthese members may be customized in light of a desired amount oftranslational motion.

While various embodiments of the motion conversion system have beendescribed, it may be apparent to those of ordinary skill in the art thatmany more embodiments and implementations are possible that are withinthe scope of this system. Although certain aspects of the motionconversion system may be described in relation to specific techniques orstructures, the teachings and principles of the present system are notlimited solely to such examples. All such modifications are intended tobe included within the scope of this disclosure and the present motionconversion system and protected by the following claim(s).

What is claimed is:
 1. A microelectromechanical system (MEMS) device,comprising: a first hinge support; a first lever supported on the firsthinge support for pivotal movement about a first hinge axis; a secondhinge support laterally spaced from the first support; a second leversupported on the second hinge support for pivotal movement about asecond hinge axis; and a lateral member having a first end supported ona first end of the first lever for pivotal movement about a third hingeaxis, and having a second end supported on a first end of the secondlever for pivotal movement about a fourth hinge axis; the first hingesupport, first lever, second hinge support, second lever and lateralmember being relatively configured and dimensioned so that movement ofsecond ends of the first and second levers in a direction will pivot thefirst ends of the first and second levers to cause movement of thelateral member in an opposite direction.
 2. The device of claim 1,wherein the first, second, third and fourth hinge axes are horizontalaxes, and the movement of the second ends of the first and second leversin a vertical direction will cause movement of the lateral member in anopposite vertical direction.
 3. The device of claim 2, wherein each ofthe first and second ends of the lateral member includes a bifurcatedportion vertically spaced from a cross portion extending betweenbifurcations of the bifurcated portion; and each of the first and secondlevers includes a tongue portion captured between the respectivebifurcated and cross portions of the first and second ends of thelateral member.
 4. A microelectromechanical system (MEMS) device,comprising: a first hinge support fixed in stationary position; a firstlever having first and second ends, the second end supported on thefirst hinge support for pivotal movement about a first hinge axis; asecond hinge support laterally spaced from the first hinge support, thesecond hinge support being movable relative to the semiconductorsubstrate; and a lateral member having a first end supported on thefirst end of the first lever for pivotal movement about a second hingeaxis; the first hinge support, first lever, second hinge support andlateral member being relatively configured and dimensioned so thatmovement of a second end of the first lever in a direction will pivotthe first end of the first lever to cause movement of the lateral memberin an opposite direction.
 5. The device of claim 4, wherein the firstand second hinge axes are horizontal axes, and the movement of thesecond end of the first lever in a vertical direction will causemovement of the lateral member in an opposite vertical direction.
 6. Thedevice of claim 5, wherein the first end of one of the first lever andthe lateral member includes a bifurcated portion vertically spaced froma cross portion extending between bifurcations of the bifurcatedportion; and the other of the first lever and the lateral memberincludes a tongue portion captured between the respective bifurcated andcross portions of the first end of the one of the first lever andlateral member.
 7. The device of claim 6, wherein the one of the firstlever and the lateral member is the lateral member, and the other of thefirst lever and the lateral member is the first lever.
 8. The device ofclaim 7, wherein the second hinge support is defined by the crossportion.
 9. The device of claim 4, wherein the first hinge support isfixed on a substrate comprising a semiconductor material.
 10. The deviceof claim 9, wherein the substrate includes integrated circuitcomponents.
 11. The device of claim 10, wherein the first hinge support,first lever, second hinge support and lateral member are formed as aMEMS superstructure over underlying complementary metal-oxidesemiconductor (CMOS) integrated circuit components.
 12. The device ofclaim 4, wherein the device comprises at least one of a pressure sensor,a speaker, an accelerometer, a variable capacitor or a microphone.